SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sat Apr 29 2023
Valid 292000Z - 301200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTION OF THE
CENTRAL FLORIDA PENINSULA...
...SUMMARY...
Two rounds of severe thunderstorms, with damaging winds, large hail,
and a coup[e of tornadoes, are possible across parts of Florida and
southern Georgia this afternoon, and again overnight.
...20Z Update...
The primary change to this outlook was to confine the category
2/Slight risk to the FL peninsula. A widespread precipitation shield
has overspread much of the FL Panhandle and surrounding region,
limiting buoyancy inland. Offshore across the Gulf of Mexico, deeper
convection associated with an MCS has resulted in tropospheric
overturning, lowering confidence in airmass destabilization ahead of
an approaching surface low/mid-level trough over the coastal
Southeast. Still, an instance or two of damaging gusts, large hail,
or a brief tornado remains possible. Otherwise, the previous
forecast remains on track, with severe potential remaining in place
across the FL Peninsula with the approach of the aforementioned MCS
and preceding sea-breeze convection. A second round of strong to
potentially severe storms may still occur across the FL Peninsula
later tonight into tomorrow morning with the approach of a surface
cold front.
..Squitieri.. 04/29/2023
.PREV DISCUSSION... /ISSUED 1125 AM CDT Sat Apr 29 2023/
...FL area through tonight...
A large cluster of thunderstorms over the northeast Gulf of Mexico
appears to be developing into an MCS, in advance of a pronounced
midlevel shortwave trough over the northwest Gulf coast. The
developing MCS is expected to progress east-northeastward over
central/north FL later this afternoon/evening, along and south of a
stalled front. Boundary-layer dewpoints near 70 F and surface
heating in cloud breaks will result in destabilization sufficient to
maintain the MCS and an attendant threat for damaging winds late
this afternoon. Aside from the MCS, cyclogenesis appears likely
near the Southeast Atlantic coast along the stalled front by
tonight, as the Gulf of Mexico shortwave trough begins to phase with
a deep low over the Great Lakes.
There will be some threat for additional storm development overnight
in association with the primary Gulf of Mexico shortwave trough and
cold front, in the wake of the afternoon MCS. Wind profiles will
strengthen with time tonight with the approach of the shortwave
trough and cyclogenesis. However, the main concern overnight will
be any reductions in moisture/buoyancy by today's convection.
Other storms may form this afternoon along the Atlantic coast sea
breeze from southeast into east central FL. MLCAPE in excess of
2500 J/kg and effective bulk shear of 35-50 kt (driven by relatively
weak low-level flow and stronger flow aloft) will support the
potential for organized/supercell storms with the potential to
produce isolated large hail and damaging winds.
...Coastal Carolinas late this afternoon into tonight...
The surface warm/moist sector will remain near the Atlantic coast
this afternoon, and an isolated strong storm may form along the
boundary this afternoon in southern NC. By tonight, there will be a
gradual increase in vertical shear in response to cyclogenesis, as
well as the possibility of a remnant MCV emerging from the Gulf of
Mexico MCS. There will be a conditional threat for
organized/supercell storms, though the details of thunderstorm
coverage/evolution will depend on the future influence of the Gulf
of Mexico convection, which is still uncertain this far northeast.
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